Native plant community recovery after Carpobrotus (ice plant) removal on an island — results of a 10‐year project

Abstract

Species of the genus Carpobrotus, or iceplant, are succulent mat-forming perennial herbs often introduced for soil stabilization. They are common in coastal environments and may thus threaten island biodiversity. While their effects are well known on soils, plant communities and associated fauna, the effects of Carpobrotus control on vegetation recovery is poorly documented. The aim of the paper is to describe plant community trajectories after Carpobrotus removal. Location Bagaud: a 58-ha Mediterranean island, southern France. Methods Carpobrotus and its litter were removed in 2011-2012. Follow-up controls of germinations and resprouts were carried out from then on. Plant communities were surveyed every year two years before and seven years after Carpobrotus removal: on two ca. 0.5-ha sites (one coastal and one inland) and in three native plant communities used as potential references. Differences in resprouts, vegetation parameters, Bray-Curtis similarity indices between years were tested. Plant community dynamics was studied through a NMDS and two recovery indices. Results The removal of Carpobrotus and its litter led to the recovery of diverse native plant communities. To prevent Carpobrotus return and ensure success, follow-up controls were necessary for a period of at least seven years, but the amount of work decreased with time. The plant community recovering on the coastal site quickly reached a composition and structure similar to that of noninvaded coastal vegetation, although some slow-growing native species remain under-represented (e.g. Crithmum maritimum and Limonium pseudominutum). The plant community recovering on the inland site was still very different from the surrounding matorral vegetation because of its slow colonization dynamics, particularly in the presence of competitive herbaceous species. Conclusion Both sites now provide diverse native plant communities with a more diversified composition and structure (plant heights, litter, bare ground patches) than the plant communities which used to be associated with Carpobrotus mats.

Beetle assemblage dynamics after invasive ice plant (Carpobrotus) removal on a small Mediterranean island

“…Arthropod communities can converge to natural configurations within a few years after Carpobrotus is removed and replaced with native vegetation on Californian coastal dunes (Knapp 2014) This project monitored beetle populations before and after the removal of a quasi-solid Carpobrotus mat with a thick, slowly decomposing litter. Native vegetation recolonized the site well (Buisson et al 2020b) and created a range of microhabitats more diverse between seasons than Carpobrotus, inducing higher taxonomic and functional diversity in the beetle assemblages. Detailed monitoring, not only of vegetation dynamics but also of arthropod assemblages, was important for understanding how changes in the abundance of species influenced their interactions and ecosystem processes.…”

Impacts of the removal of invasive Carpobrotus on spider assemblage dynamics

“…(ii) the matorral site is a low matorral community without Carpobrotus, characterized by Cistus monspeliensis, Cistus salviifolius, E. arborea, P. lentiscus, Phillyrea angus-tifolia, and Smilax aspera. Vegetation dynamics are slow at this site and this plant community was considered to be stable over the study period (Buisson et al 2020).…”

“…uprooting, herbicide or biological control; Campoy et al 2018). However, detailed monitoring is uncommon: Chenot et al (2018) studied the effect of Carpobrotus removal on soil erosion and native vegetation by performing experiments in small plots over a short period; Krebs et al (2015) and (Buisson et al 2020) studied the effect of Carpobrotus removal on native plant recolonization on a 1-ha area, over several years.…”

Demographic analysis of an Israeli Carpobrotus population

“…Manual removal is feasible for accessible populations, and it may or may not be optimal to follow this up with the removal of dead shoots and litter. Leaving litter increases the risk Carpobrotus germination from seed and slows recovery of native plants, but decreases the problem of erosion, which is an important issue in sites with steep slopes [13,23,25]. Effective mortality of Carpobrotus and rapid recovery of native vegetation has also been demonstrated with chemical control using Glyphosate [18,24].…”

“…Carpobrotus disruptions to biotic and abiotic processes can hinder management efforts as they can persist for years after the invasion has been eradicated [21,22]. However, several restoration projects have successfully eradicated or reduced Carpobrutus populations and restored native plant and animal communities using either manual or chemical removal methods [13,[23][24][25]. In Europe, conservation areas have dedicated~1,000,000 EUR/year to controlling Carpobrotus invasions [8,[26][27][28].…”